One-zone synchrotron self-Compton model for the core emission of Centaurus A revisited

Πετροπούλου, Μαρία; Lefa, Eva; Dimitrakoudis, Stavros; Mastichiadis, A.

doi:10.1051/0004-6361/201322833

Cited by 47 publications

(53 citation statements)

References 69 publications

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“…The large values of γ e,min used in this work to describe the SEDs imply that electrons are efficiently accelerated by the Fermi mechanism only above this energy, and below this energy they are accelerated by a different mechanism that produces the hard electron distribution. The proton luminosity is computed using the charge neutrality condition to justify a comparable number of electrons and protons (N e =N p ; Böttcher et al 2013;Sikora et al 2009;Abdo et al 2011;Petropoulou et al 2014;Fraija et al 2017). The value of proton luminosity found corresponds to a small fraction (∼ 10 −2 ) of the Eddington luminosity L Edd ∼ 2.5 × 10 46 erg/s which is estimated by considering the value of supermassive black hole (2 × 10 8 M ; Barth et al 2003).…”

Section: Modeling the Spectral Energy Distributionmentioning

confidence: 99%

Long-term Optical Polarization Variability and Multiwavelength Analysis of Blazar Mrk 421

Fraija

Benítez

Hiriart

et al. 2017

ApJS

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The results of 8-year R-band photopolarimetric data of blazar Mrk 421 collected from February 2008 to May 2016 are presented, along with extensive multiwavelength observations covering from radio to TeV γ-rays around the flares observed in May 2008, March 2010, and April 2013. The most important results are found in 2013 when the source displayed in the R-band a very high brightness state of 11.29 ± 0.03 mag (93.60 ± 1.53 mJy) on April 10th and a polarization degree of (11.00 ± 0.44)% on May 13th. The analysis of the optical data shows that the polarization variability is due to the superposition of two polarized components that might be produced in two distinct emitting regions. An intranight photopolarimetric variability study carried out over 7 nights after the 2013 April maximum found flux and polarization variations on the nights of April 14, 15, 16 and 19. In addition, the flux shows a minimum variability timescale of ∆ t =2.34±0.12 hours, and that the polarization degree presented variations of ∼ (1 -2) % in a timescale of ∆ t ∼ minutes. Also, a detailed analysis of the intranight data shows a coherence length of the large-scale magnetic field of l B 0.3 pc which is the same order of magnitude to the distance traveled by the relativistic shocks. This result suggests that there is a connection between the intranight polarimetric variations and spatial changes of the magnetic field. Analysis of the complete R-band data along with the historical optical light curve found for this object shows that Mrk 421 varies with a period of 16.26 ± 1.78 years.

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Section: Modeling the Spectral Energy Distributionmentioning

confidence: 99%

Long-term Optical Polarization Variability and Multiwavelength Analysis of Blazar Mrk 421

Fraija

Benítez

Hiriart

et al. 2017

ApJS

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“…Rieger & Aharonian (2009) propose that CenA is dominated by ADAF emission, which they use to predict that CenA might be a source of TeV photons and ultra-high-energy (UHE) cosmic rays. While the latter claim is disputed in the literature (Petropoulou et al 2014, who instead favor a twozone SSC model,with UHE particles emerging from the lobes, but see also Khiali et al 2015 for a model using magnetic reconnection to produce γ-rays), a large ADAF can explain the observed hard X-ray properties. Typical temperatures for the electrons in an ADAF Comptonization plasma are on the order of 100 keV, in good agreement with our measurement.…”

Section: The Geometry and Physics Of The X-ray Coronamentioning

confidence: 99%

NuSTAR AND XMM-NEWTON OBSERVATIONS OF THE HARD X-RAY SPECTRUM OF CENTAURUS A

Fürst

Müller

Madsen

et al. 2016

ApJ

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We present simultaneous XMM-Newton and Nuclear Spectroscopic Telescope Array (NuSTAR) observations spanning 3-78 keV of the nearest radio galaxy, CentaurusA (Cen A). The accretion geometry around the central engine in CenA is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the central region of CenA with subarcminute resolution at X-ray energies above 10 keV for the first time, but found no evidence for an extended source or other off-nuclear point sources. The XMM-Newton and NuSTAR spectra agree well and can be described with an absorbed power law with a photon index Γ=1.815±0.005 and a fluorescent Fe Ka line in good agreement with literature values. The spectrum does not require a high-energy exponential rollover, with a constraint of E fold >1 MeV. A thermal Comptonization continuum describes the data well, with parameters that agree with values measured by INTEGRAL, in particular an electron temperature kT e between ≈100-300 keV and seed photon input temperatures between 5 and 50 eV. We do not find evidence for reflection or a broad iron line and put stringent upper limits of R<0.01 on the reflection fraction and accretion disk illumination. We use archival Chandra data to estimate the contribution from diffuse emission, extra-nuclear point sources, and the outer X-ray jet to the observed NuSTAR and XMM-Newton X-ray spectra and find the contribution to be negligible. We discuss different scenarios for the physical origin of the observed hard X-ray spectrum and conclude that the inner disk is replaced by an advection-dominated accretion flow or that the X-rays are dominated by synchrotron self-Compton emission from the inner regions of the radio jet or a combination thereof.

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“…Although this calculation was performed for acceleration of non-relativistic particles, can be seen that as the velocity of the shock increases, the ratio of proton and electrons densities decreases, tending to be similar (see table 1 , Bell 1978). Due to the fact that the minimum Lorentz factor cannot be determined just assuming the standard scenario of injection and acceleration, it is reasonable to use charge neutrality to justify a comparable number of electron and protons (Böttcher et al 2013;Sikora et al 2009;Abdo et al 2011;Petropoulou et al 2014). Requiring that electron and proton number densities are similar (Ne Np), we have calculated that the minimum proton Lorentz factors used to describe the TeV γ-ray fluxes in high and low states are γp,min = 8 × 10 3 and 5 × 10 4 , respectively.…”

Section: One Electron and Proton Populationmentioning

confidence: 99%

Modeling the spectral energy distribution of the radio galaxy IC310

Fraija

Marinelli

Galván-Gaméz

et al. 2017

Astroparticle Physics

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The radio galaxy IC310 located in the Perseus Cluster is one of the brightest objects in the radio and X-ray bands, and one of the closest active galactic nuclei observed in very-high energies. In GeV -TeV γ-rays, IC310 was detected in low and high flux states by the MAGIC telescopes from October 2009 to February 2010. Taking into account that the spectral energy distribution (SED) up to a few GeV seems to exhibit a double-peak feature and that a single-zone synchrotron self-Compton (SSC) model can explain all of the multiwavelength emission except for the non-simultaneous MAGIC emission, we interpret, in this work, the multifrequency data set of the radio galaxy IC310 in the context of homogeneous hadronic and leptonic models. In the leptonic framework, we present a multi-zone SSC model with two electron populations to explain the whole SED whereas for the hadronic model, we propose that a single-zone SSC model describes the SED up to a few GeVs and neutral pion decay products resulting from pγ interactions could describe the TeV -GeV γ-ray spectra. These interactions occur when Fermi-accelerated protons interact with the seed photons around the SSC peaks. We show that, in the leptonic model the minimum Lorentz factor of second electron population is exceedingly high γ e ∼ 10 5 disfavoring this model, and in the hadronic model the required proton luminosity is not extremely high ∼ 10 44 erg/s, provided that charge neutrality between the number of electrons and protons is given. Correlating the TeV γ-ray and neutrino spectra through photo-hadronic interactions, we find that the contribution of the emitting region of IC310 to the observed neutrino and ultra-high-energy cosmic ray fluxes are negligible.

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One-zone synchrotron self-Compton model for the core emission of Centaurus A revisited

Cited by 47 publications

References 69 publications

Long-term Optical Polarization Variability and Multiwavelength Analysis of Blazar Mrk 421

Long-term Optical Polarization Variability and Multiwavelength Analysis of Blazar Mrk 421

NuSTAR AND XMM-NEWTON OBSERVATIONS OF THE HARD X-RAY SPECTRUM OF CENTAURUS A

Modeling the spectral energy distribution of the radio galaxy IC310

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